Chem of Life

Macromolecules:Nucleic Acids

Nucleic Acids

• Biomolecules• Store and Transmit Hereditary Information

Examples (Types) of Nucleic Acids

• Deoxyribonucleic Acid (DNA)• Ribonucleic Acid (RNA)

DNA Functions

• Provides directions for its own replication• Direct RNA synthesis• & through RNA controls protein synthesis

Genes

• Consist of DNA (a nucleic acid polymer)• Molecules that enable living organisms to

reproduce their complex components from one generation to the next.

DNA

• Inherited from parents• Each chromosome contains one long DNA

molecule with several hundred to more than a thousand genes)

• Copied before cell division to be passed onto next generation.

Molecular Structure:

• Monomer: nucleotide• Each nucleotide monomer consists of:– A phosphate group– Pentose sugar– Nitrogenous base

RNA Structure

• Polynucleotide:– Pentose Sugar = Ribose– Nitrogenous base (a purine or a pyrimidine)– Phosphate group

• Simple polynucleotide (single strand)

RNA

DNA Structure

• Polynucleotide:– Pentose Sugar = deoxyribose– Nitrogenous base (a purine or a pyrimidine)– Phosphate group

• Double Stranded

DNA

Ribose vs. Deoxyribose

• Deoxyribose lacks an Oxygen atom on the second C in the ring

FYI

• Numbered Carbons have a prime (‘) after them, note the 5’ C end is the one that sticks out from the ring.

• The phosphate group attached to the 5’ C of the ring

Recap

• Nucleic Acid Polymer = polynucleotides– Examples: DNA & RNA

• Nucleic Acid Monomer = nucleotide– Nucleoside (nitrogenous base & pentose)– Phosphate group

Nitrogenous Bases

• Two families:– Pyrimidine– Purine

Pyrimidine:

• 6-membered ring & N atoms– N atoms take up the H+ from solution (base)

• Members include:– Cytosine (C)– Thymine (T)• (found only in DNA)

– Uracil (U) • (found only in RNA)

Pyrimidine:

Purines

• Larger 6-membered ring fused to a 5-membered ring

• Members include:– Adenine (A)– Guanine (G)

Purines

Nitrogenous BaseFunctional Groups

• Vary • Attached to the rings

(Handout)

Polymerization

• Adjacent nucleotides are joined by covalent bonds (phosphodiester linkages)

• Involves the –OH group on 3’ C of one nucleotide to the phosphate group on the 5’ C of another nucleotide

Polymerization

• Result = backbone with repeating sugar-phosphate with a distinct 3’ and 5’ ends– DNA (The 2 sugar phosphate strands run in

opposite directions = antiparallel) • The nitrogenous bases stick out like

appendages and are complementary in DNA.

Biological Staining:

• Acridine orange (AO) is a nucleic acid selective fluorescent cationic dye useful for cell cycle determination. It is cell-permeable, and interacts with DNA and RNA by intercalation or electrostatic attractions. When bound to DNA, it is very similar spectrally to fluorescein. Like fluorescein, it is also useful as a non-specific stain for backlighting conventionally stained cells on the surface of a solid sample of tissue (fluorescence backlighted staining[4]).

Wells J. (1988) A Technique for Staining the Superficial Cells of Plucked Hair Follicles and Other Solid Tissues, Stain Technology, Vol 63, No3.

Resources:

• http://www.millerandlevine.com/chapter/12/bases.html

• http://www.biologycorner.com/bio1/DNA.html

• 2006 Miller & Levine Prentice Hall Biology• 2005 Campbell & Reece Biology 7th ed